Composite sheets made by entangling continuous filaments with pulp fibers under a water stream have been known from, for example, JPA No. 179545/93 entitled "Nonwoven composite fabric with a high pulp content" and JPA No. 214654/93 entitled "A process for producing wiping cloth". These inventions represent advanced techniques in the field of wipers which overcame the disadvantageous decrease in the strength of wood pulp fiber sheets in a wet state by combining them with a continuous filament web. These techniques succeeded in conferring a high wet strength to paper wipers while maintaining excellent characteristics thereof such as water and oil absorption, low cost, etc., thus enabling them to be used like fabric wipers.
However, these techniques can be actually put into practice only by using spun-bonded nonwoven fabrics with a low density per unit area (20 g/m.sup.2 or less) as the continuous filament web due to problems of costs, strength, etc. Spun-bonded nonwoven fabrics with a low density per unit area have a biased fiber orientation mostly toward machine direction. As a result, a great difference arises in tensile strength and elongation between machine and cross direction simply by combining a spun-bonded nonwoven fabric with pulp fibers by entanglement under a water stream.
Commercially available wiping cloths made from a complex of a spun-bonded nonwoven fabric and pulp fibers also involve anisotropy between machine and cross directions as shown in Table 1. This table reports the measurements of breaking loads and elongations at breakage in tensile tests in machine and cross directions. The machine direction here means a direction which is parallel to lines formed by entanglement under a water stream in the direction of the stream. The results of measurement in both commercial products show that breaking loads are twice or more in the machine direction than in the cross direction and elongations are 1.9 times or more in the cross direction than machine direction. These anisotropies do not affect basic performances for wipers such as water/oil absorption, wiping properties, etc., but greatly affect usability during a wiping operation. These products are characterized by their high strength equal to fabric wipers as compared with paper wipers.
However, an anisotropy between machine and cross directions of a sheet, particularly a difference in elongation, provide an unpleasant texture as compared with fabric wipers. For example, a wiper made from a low-elongation material should be used with care of orientation because it is readily broken by a metal projection on the object to be wiped.
The above-mentioned commercial products (Table 1) are poor in draping qualities (suppleness, softness) and rather inferior to fabric wipers in touch. Water-stream entangled nonwoven fabrics using staple fibers such as synthetic fibers (such as polyester fibers, polypropylene fibers, nylon fibers, acrylic fibers, etc.), rayon, cotton, etc. have nearly fabric-like draping qualities. These fibers have the advantage that they are bonded more weakly than pulp fibers so that the resulting sheet is not so stiff as paper, but are not a realistic alternative to a fabric wiper due to high costs.